Daily average solar zenith angle weighted by insolation

1
Daily average solar zenith angle weighted by
insolation
Motivation albedo depends on zenith angle
2
PLANETARY ALBEDO - Annual mean
3
PLANETARY ALBEDO
JJA
DJF
4
OUTGOING LW RADIATION -Annual mean
5
OUTGOING LW RADIATION
JJA
DJF
6
NET (SWLW) TOA RADIATION - Annual mean
7
NET (SWLW) TOA RADIATION
JJA
DJF
8
Zonal average of annual mean absorbed solar,
emitted longwave, and net radiation
Gain energy in tropics, lose at higher latitudes
9
2.9 Poleward energy transport
In the annual mean, ?Eao / ?t 0, so RTOA ?Fao
2-D example (tropics)
RTOA
?Fao Fao(???) - Fao(?)
Fao(???)
Fao(?)
Atm and ocn
10
Note that you can integrate RTOA from the south
pole to get total energy flux across each
latitude belt (note that Fao(south pole) 0)
RTOA
Fao(?)
Latitude ?
South pole (Fao 0)
11
Northward heat transport across each latitude
(1PW1015W)
Trenberth and Caron (J Clim v14 p3433 2001) Solid
line - atmocn transport Dashed - ocn only
dash-dot - atm only
12
Heat transport by the individual oceans (two
different estimates positive implies northward
transport)
13
3. Atmospheric Radiative Transfer and Climate
3.2 Electromagnetic radiation Speed c3x108
m/s Speed, frequency(?) and wavelength(?)
related by c ? ? Energy of a photon
depends on frequency E? h ? h6.625x10-34Js
Plancks constant Radiation can be transmitted,
scattered, or absorbed by objects
14
(source KKC Ch3)
Sun 100nm to 4 ?m (1nm10-9m ?m10-6m) UV
(1), visible and near infrared (99) Earth
4-200 ?m - thermal infrared
15
3.3 Description of radiative energy The energy of
radiation is measured through the intensity I?.
Its a function of time, position, frequency, and
direction. We are usually interested in the
total energy per unit frequency passing across a
unit plane area from one side to another. We
find this by integrating the intensity projected
onto the normal of the plane, over all solid
angles Spectral flux density F ? ?02p ?0p/2
I?(?,?) cos ? sin ? d? d?
ç
d?
Intensity normal to plane of dA
Integrate over hemisphere
Integrate over all frequencies to get flux
density in W/m2 F ?0? F ? d?